By Ainur Romah

TUBAN, Indonesia 

Police have arrested at least seven people on suspicions of conspiring to overthrow the Indonesian government.

The arrests took place several hours before the start of a large rally Friday to demand the arrest of Jakarta Governor Basuki "Ahok" Tjahaja Purnama on blasphemy charges.

Police spokesman Inspector General Boy Rafli Amar was quoted as saying by kompas.com Friday that those detained were being held for plotting treason.

"[Those] who have been arrested, have been determined as suspects," he said.

The Jakarta Post reported that a message circulating among journalists suggests that among those arrested were a well known musician-cum-politician, a retired two-star army general, a former lawmaker, and the sister of former president and ruling Indonesian Democratic Party of Struggle Chair Megawati Soekarnoputri.

Amar said that the plot aimed to mobilize the hundreds of thousands taking part in Friday's rally.

"[They] intend to invite and incite [demonstrators] to overthrow the legitimate government," he said.

He added that those arrested were not connected to the protest, but wanted to take advantage of the numbers to reach their goals.

"[They want] to revoke the mandate of President Jokowi Joko Widodo and Vice president Jusuf Kalla and form a transitional government," detik.com. quoted Amar as saying.

He said that police had been aware of their activities for three weeks, and would decide in the next 24 hours if they will continue to be detained.

Friday's protest -- named "Action to Defend Islam III" -- was the latest in a wave of sprawling protests to descend on the capital to demand the acceleration of legal proceedings against Ahok.

He is accused of publicly insulting Islam, however he says he was calling for people not to be “deceived” by those using one of Quran's verses, Al Maidah: Chapter 51, not that the verse itself was insulting.

Around 13 different parties have reported him to the police on charges of defamation.